The present disclosure relates to an electric power supplying apparatus which is capable of utilizing an A.C. (alternating current) electric power from an external electric power system and an output electric power from an electric storage device, an electric power supplying method used in the same, an inverter used in the same, and an electric vehicle including the same.
When an amount of electric power supply from an external electric power system (referred to as “a commercial utility power source, a grid or the like”) is reduced due to an accident or the like, or an electric power demand is seasonally increased, the fear that the electric power demand is increased for the amount of electric power supply, and thus a sudden electric power outage is caused is generated in some cases. In addition thereto, it is supposed that the electric power outage is caused due to a disaster such as torrential rain or lightning stoke.
Heretofore, it is known to use an Uninterruptable Power Supply (UPS) which supplies an electric power to a peripheral apparatus such as a computer when an electric power failure such as an electric power outage is caused. This technique, for example, is disclosed in Japanese Patent Laid-Open No. 2011-045176. However, the existing UPS is such an apparatus that is effective in the electric power outage for a short time, and temporarily supplies the electric power to the computer and the peripheral apparatus. Therefore, the existing UPS is insufficient for supplying an in-home electric power in a phase of generation of large-scale electric power outage for a long time. In addition thereto, there is caused a problem that the existing UPS is operated in the phase of the electric power outage and, for example, cannot be used in a use application in which a used amount of external electric power system in the home is reduced.
Recently, an at-home electric storage device having a larger capacity has been put to practical use. Utilization of the at-home electric storage device results in that the electric power supply in the phase of the electric power outage can be ensured, and the electric power demand and the used amount of electric power of the external electric power system can be both reduced. For example, it is expected that the supply of the A.C. electric power from the external electric power system is reduced to compensate for the insufficient electric power by the electric storage device. In addition thereto, there is caused the fear that the electric power demand in the home is increased to exceed a contracted electric power contracted with an electric power provider, and thus a breaker is actuated to cut out the electric power. In such a case, an output electric power from the electric storage device is supplied, thereby making it possible to avoid such a case as for the in-home electric power to exceed the contracted electric power.
Japanese Patent Laid-Open No. 2011-223731 describes that a system for supplying an A.C. electric power of an external electric power system to a load, and a system for outputting an A.C. electric power into which an output electric power from an electric storage device is converted by an inverter are switched over to each other. Also, Japanese Patent Laid-Open No. 2011-083060 describes that an output electric power from a solar cell, and an output electric power from an electric storage device are mixed with each other, and the resulting output electric power is outputted.
In addition, recently, a power generating apparatus utilizing a recyclable energy from a solar power generation system, a wind power generation system, or the like is installed in homes in many cases. The electric storage device can be charged with the electricity from an electric power generation output from this sort of electric power generating apparatus. In the case of the solar electric power generation system, a purchase system in which the electric power provider purchases the generated electric power is widely operated. The purchase system is classified into a full amount purchase system for purchasing a full amount of electric power by the solar power generation, and a purchase system for purchasing a remaining electric power (referred to as “a surplus electric power”) which is obtained by subtracting an amount of consumed electric power from an amount of electric power by the solar electric power generation. The surplus electric power purchase system is the current Japanese system.
Therefore, a use application of the generated electric power by the solar electric power generation system includes a use application in which the generated electric power by the solar electric power generation system is submitted together with the system electric power for the at-home electric power, a use application in which the generated electric power by the solar electric power generation system is submitted for the charging electric power for the electric storage device, and a use application in which the generated electric power by the solar electric power generation system is subjected to the reverse electric power flow to be submitted for the electric power selling. In the related art as well, Japanese Patent Laid-Open No. 2011-172334 describes that a charging current value for a battery is limited based on a remaining capacity of the battery, a load-used electric power pattern, and an electric power generation estimating pattern, whereby the battery is prevented from being charged with the electricity from an excessive charging current value.